Laser surgery, and in particular laser surgery of soft oral tissues is broadly accepted in current practice because of several advantages of laser scalpel over traditional cold scalpels or other surgical means such as electrosurgery. Laser surgery advantages include reduced pain and need for anesthesia, reduced postoperational discomfort, instant tissue coagulation and hemostasis, and automatic sterilization of the operation field.
The most affordable and popular types of dental surgical lasers operate in the near infrared spectral wavelength range of 810 to 1100 nm due to technical progress in semiconductor GaAs lasers which made it possible to generate sufficient laser power in relatively low-cost, simple, reliable, and energy-efficient semiconductor devices. It is well known that light absorption in the biotissue is relatively low in this spectral range and insufficient to produce localized tissue cutting with minimal collateral damage of normal tissue.
Therefore, the dominat mechanism of the laser surgery in this spectral range is associated with so called “hot tip”, when optical tip or just the distal end of a fiber optic light delivery system absorbs laser light due contaminated to the tip carbonized tissue, black paper, corn or other material, heats to a high temperature and then performs surgical action because of that high temperature and heat conduction from the “hot tip” to the tissue, rather than by direct interaction of the laser light with the tissue. Such behavior of a laser scalpel tip is typical for contact surgery with different wavelength. The tissue in contact with distal end of the tip is exposed to a high power density and generates heat which can heat up the tip due to heat conduction. The tip is becomes hot, and temperature of the contact tip during surgery can be elevated to 1500° C. or higher. As a result, the tip may melt during surgery and be destroyed.
Due to these phenomena, the cutting efficiency and thermal effect on the tissue during surgery experience uncontrollable change which can result in lack of confidence for surgeons and can be the reason for excessive collateral tissue damage and post-surgery complications. Non-contact surgery is more predictable but it is less convenient for surgeons because it requires a different and new non-tactile skill and art. Also, non-contact surgery requires lasers with wavelengths in the range of 1.8-11 microns which are highly absorbed in the tissue and are substantially more expensive than GaAs diode lasers.